Simultaneous self- and mutual capacitance sensing

Abstract

A touch controller. The touch controller can include first sense circuitry configured to be coupled to a first electrode on a touch sensor panel, the first sense circuitry configured to sense a first self-capacitance associated with the first electrode, and a first mutual capacitance associated with the first electrode. In some examples, the first sense circuitry can be configured to sense the first self-capacitance and the first mutual capacitance simultaneously. In some examples, the touch controller can further include a first mixer and a second mixer coupled to the first sense circuitry, the first mixer configured to demodulate a first output from the first sense circuitry to extract information about the first self-capacitance from the first output, the second mixer configured to demodulate the first output from the first sense circuitry to extract information about the first mutual capacitance from the first output.

Description

FIELD OF THE DISCLOSURE[0001]This relates generally to touch sensor panels, and more particularly to touch sensor panels in which self-capacitance and mutual capacitance are sensed.BACKGROUND OF THE DISCLOSURE[0002]Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel...

AI Technical Summary

Benefits of technology

[0004]Some capacitive touch sensor panels can be formed by a matrix of substantially transparent conductive plates made of materials such as Indium Tin Oxide (ITO), and some touch screens can be formed by partially integrating touch sensing circuitry into a display pixel stackup (i.e., the stacked material layers forming the display pixels). Additionally, some capacitive touch sensor panels can be formed by rows and columns of substantially transparent conductive lines made of materials such as ITO, and can similarly form touch screens with touch sensing circuitry partially integrated into a display pixel stackup. Touch events can be sensed on the above touch sensor panels by detecting changes in the self-capacitance and / or mutual capacitance of the above conductive plates and / or lines. In some examples, the touch sensor panels can simultaneously sense self-capacitance and mutual capacitance. In some examples, one or more capacitances can cause offsets in the self-capacitance measurements that can reduce the dynamic range of corresponding sensing circuits, and can make touch detection difficult. The examples of the disclosure provide various techniques for reducing the offset effects of such capacitances.

Problems solved by technology

In some examples, one or more capacitances can cause offsets in the self-capacitance measurements that can reduce the dynamic range of corresponding sensing circuits, and can make touch detection difficult.